The flow of migrants from North Africa into southern Europe is no new thing. It has been going on for decades, but now it’s become the stuff of tragedy as thousands cram into tiny vessels scarcely fit for a mill-pond and head off across two hundred miles of treacherous sea.

Europe is suddenly caught in a dilemma. Will it rage against illegal immigrants, or weep over the loss of thousands of lives? But behind the dilemma there is also guilt. For centuries we Europeans shamelessly took advantage of freedom of movement to turn up unbidden and unwelcome on other shores, killing native inhabitants, destroying their culture and plundering their treasures.

Today, people of European origin dominate Canada, the United States, Brazil, Argentina, New Zealand and Australia. From the ‘Mayflower’ to the ‘Metagama’, migration, driven by poverty, has been a key factor in our history. Deep-down, then, we know the heart of a migrant and the curious paradox of a mind that is filled with ‘cianalas’ and yet knows it could never forsake the comforts of central heating and air-conditioning for the romance of a peat-fire.

Europe’s movers and shakers are now calling for a concerted response to the migrant crisis, but this has not been the only note. Influential voices have also suggested that the migrants are part of a coherent plan to increase the Muslim presence in Europe, and this is even being linked to predictions that within twenty-five years Britain will be a predominantly Muslim country. Yet, while for all the years of the Cold War we trembled at the spectre of Communism and the thought of ‘Reds under the bed’, no-one seems to be taking the Islamic threat seriously.

Is such complacency wise? There can certainly be no doubt that the thousands of North Africans now pouring into Europe are Muslims. Nor can there be any doubt that after centuries of relative passivity Islam, like Scottish separatism, is now all fired-up with new energy and zeal. Quite where the fuel-injection has come from is not clear, though it probably owes something to fabulous oil-based Arab wealth, the emergence of a new generation of fanatical religious leaders and, above all, the creation of the state of Israel. But whatever the reasons, the millions of North Africans who will enter Europe in the next twenty-five years are not likely to arrive full of gratitude. They will bring with them Islam’s innate sense of superiority and its contempt for the infidel.

Equally clearly, our freedoms will never survive under a dominant Islam. No Muslim country on earth grants civil rights or liberty of speech to its citizens. In Iraq, under Saddam Hussein, even members of his own party lived in daily fear of summary execution. In Saudi Arabia, no woman may drive a car. And in the countries of the so-called ‘Arab Spring’, the spring quickly turned to winter. The toppling of Mubarak brought no freedom to Egypt and the toppling of Gadaffi brought only chaos to Libya. Islam and the ballot-box, Ayatollahs and civil liberties, can never live together.

But is the influx of Libyan refugees part of a conspiracy? It’s certainly hard to believe that it’s a pan-Islamic one. The Muslim community is too deeply divided for that, and even Islamic State is scarcely in a position to orchestrate the movement of thousands of Libyans. It is, however, perfectly capable of placing among the migrants hundreds of its own radicalised Muslims; and it is beyond belief that it hasn’t done so.

All minorities prefer to keep a low profile and avoid trouble. Generations of British Muslims have done exactly that, many have made an invaluable contribution to British society, and many are perfectly prepared to listen quietly while Christians ‘witness’ to them. But when minorities become majorities, things change, as German Jews discovered in the 1930s. Once the Nazis achieved ascendancy, friendly German neighbours suddenly became informants for the Gestapo; and in the event of Islamic dominance in Britain our friendly Muslim shopkeepers will have little option but to march behind the radicals.

Have we any protection? Tighter immigration controls bring their own complications. We cannot close our doors on asylum-seekers simply because they’re Muslims, nor can we set up border-controls which specifically target Muslims. That would simply raise the level of Islamic paranoia, and they already have countless spokesmen prepared to ‘explain’ that if Muslims behead a soldier it’s no more than a natural response to the way they were treated in school.

But have we no intellectual, ideological or spiritual barriers to raise against Islam? The prevailing secular humanism is too preoccupied with hating Christianity to notice the threat posed by Islam; and anyway, when it comes to the bit, a negative (‘There is no God’) can never have the motivational force of a fanatical positive like, ‘Allah is God’.

What of Christianity? Can it save us (and our freedoms) from Islam? Yes, but only if it is robustly biblical, and robustly confident that Jesus is the one and only Lord.

But Christianity must also address the fact that in many parts of Britain it is invisible: simply not there. Even in many parts of the Highlands, the church has now withdrawn, leaving a religious vacuum, and a generation that is spiritually spineless.

The churches speak much of mission, but usually only as part of a plea to modernise. But more, surely, is needed: a legion of formally ordained Evangelists committed to the many Scottish communities where Christ is unheard of, and where a passionate Islam would meet with no counter-faith.

But then, Islam has never needed to win the intellectual battle, and in the eyes of its radicals it still doesn’t need to. Bombs and beheadings will suffice; or, in the worst possible scenario, an Islamised France, armed to the hilt and ready to pounce.

Apocalyptic delusions of an aged brain? Possibly, but consider Augustine, the greatest Christian mind the world has ever seen. Born in Algeria, he became Bishop of Hippo (also in Algeria) in 396. There, if anywhere, Christianity seemed secure for all time coming. But by 622 Mohammed had established himself in Medina, and a hundred years later Christianity was obliterated in Algeria. It was no victory of the mind. Augustine’s diocese had merely been overwhelmed by a Muslim army.

History need not repeat itself. But let’s not sleep-walk our way into the loss of all our freedoms.